As someone who uses (or used to use) Steam Link to be able to use a Windows PC headlessly to game from a macOS machine, I think it's a really compelling argument to consider it before considering a Steam Deck.
However, I'm viewing Steam Deck as a mobile gaming machine, which might be replacing my current Windows gaming laptop, and I can leave my Windows gaming laptop at home (or replace with a tower altogether). And if Steam Link works with a Steam Deck, I can have the best of both worlds (mobile gaming + regular gaming via Steam Link)!
However, I'm viewing Steam Deck as a mobile gaming machine, which might be replacing my current Windows gaming laptop, and I can leave my Windows gaming laptop at home (or replace with a tower altogether). And if Steam Link works with a Steam Deck, I can have the best of both worlds (mobile gaming + regular gaming via Steam Link)!